Spaceflight Insider

WGS-10 satellite launches atop ULA’s Delta IV rocket

A United Launch Alliance Delta IV rocket orbits the WGS-10 satellite for the U.S. Air Force. Photo Credit: Michael McCabe / SpaceFlight Insider

A United Launch Alliance Delta IV rocket orbits the WGS-10 satellite for the U.S. Air Force. Photo Credit: Michael McCabe / SpaceFlight Insider

CAPE CANAVERAL, Fla — Following a two-day slip to analyze off-nominal data indications, a United Launch Alliance Delta IV rocket took to the skies to send the 10th Wideband Global SATCOM (WGS-10) satellite into space for the U.S. Air Force.

Liftoff took place at 8:26 p.m. EDT March 15 (00:26 GMT March 16), 2019, from Space Launch Complex 37B at the Cape Canaveral Air Force Station.

“We are very proud to deliver this critical asset to orbit in support of the U.S. and Allied warfighters deployed around the world defending our national security,” Gary Wentz, ULA vice president of Government and Commercial Programs, said in a ULA news release. “Thank you to the entire ULA team and mission partners for their outstanding teamwork and dedication to mission success.”

The launch took place about 90 minutes into the more-than-two-hour launch window because of several anomalies during the countdown. First, an issue earlier in the countdown that caused teams to fall behind schedule requiring a 15-minute delay.

The Delta IV Medium in the hours before launch. Photo Credit: Scott Schilke / SpaceFlight Insider

The Delta IV Medium in the hours before launch. Photo Credit: Scott Schilke / SpaceFlight Insider

Second, closer to the 7:11 p.m. EDT (23:11 GMT) target, it was found that an issue with the rocket’s pneumatic system would require more time to troubleshoot. Additionally, an out-of-bounds reading in a liquid oxygen pressure sensor cropped up, but both issues were resolved and the mission was able to get underway with a time set for 7:52 p.m. EDT (23:52 GMT).

However, then a “resolution” issue with NASA’s Tracking and Data Relay Satellite System (used to relay rocket telemetry during flight) was noticed, requiring a further delay into the window to 8:26 p.m. EDT (00:26 GMT March 16).

What was scheduled as the next-to-last flight of the Delta IV single stick and the final in the Medium+ (5,4) configuration, the rocket consists of a Common Core Booster equipped with an Aerojet Rocketdyne built RS-68A engine that burns a combination of liquid hydrogen and liquid oxygen.

The RS-68A engine provides 705,000 pounds (3,100 kilonewtons) of thrust at sea level. In order to provide the additional lift capability to put the payload into its intended super-synchronous transfer orbit, the rocket is also equipped with four Northrup Grumman-built solid rocket motors, each providing 281,000 pounds (1,250 kilonewtons) of thrust. A 5 meter fairing tops the rocket and encapsulates the spacecraft to protect it from the launch environment on ascent.

WGS-10 is a Boeing-built satellite and is part of the highest-capacity satellite communication system for the U.S. Department of Defense, according to ULA. The satellite is a Block II follow-on spacecraft and the fourth to be deployed into the WGS constellation.

The satellites provide communications in the X-band and Ka-band spectrum, however the Block I previously deployed can filter and downlink up to 4.41 GHz while WGS-10 can downlink nearly double that at 8.09 Ghz of bandwidth.

The Delta IV Medium with WGS-10 encapsulated in the payload fairing on top. Photo Credit: Michael McCabe / SpaceFlight Insider

The Delta IV Medium with WGS-10 encapsulated in the payload fairing on top. Photo Credit: Michael McCabe / SpaceFlight Insider

The flight began five seconds before liftoff with the ignition of the Delta IV’s RS-68A main engine, after clearing a series of checks, the flight computer ignited the four solid rocket boosters with liftoff of the 218-foot (65-meter) rocket occurring at T-minus zero seconds.

The rocket then performed it’s roll maneuver, which placed it on its desired trajectory. At T-plus 46 seconds, the vehicle then passed through the area of Maximum Dynamic Pressure, or Max-Q, where the aerodynamic forces placed on it by the speed of the vehicle and the air pressure are at their maximum.

Ninety-two seconds into the flight the first pair of SRBs burned out followed by the second pair just 2 seconds later, both pairs were ejected 8 seconds after they burned out. Burning fuel at a rapid rate, the rocket now weighed almost half of what it did at liftoff.

The Delta IV Common Booster Core’s RS-69A engine continued to propel the vehicle on its desired trajectory and 3 minutes and 14 seconds into the flight, the vehicle was well out of the thick atmosphere and the payload fairing was jettisoned exposing the satellite.

Having expended its supply of liquid hydrogen and liquid oxygen, main engine cutoff occurred 3 minutes and 56 seconds into the flight. Stage separation occurred 6 seconds later.

The Delta Cryogenic Second Stage (DCSS) powered by single RL10B-2 engine producing 24,750 pounds (110 kilonewtons) of thrust ignited 7 seconds later.

The first burn of the DCC lasted just over 15 minutes, after which the vehicle entered a coast phase. Following the coast phase the RL10B-2 engine once again was ignited to place the WGS-10 satellite into its super-synchronous transfer orbit.

From there the satellite will use its own propulsion system to raise itself into the targeted geostationary orbit.

This was the eighth flight of the Delta IV in the Medium+ (5,4) configuration, all of which have been in support of the WGS program. This was also the 39th launch of a Delta IV since its inaugural launch in 2002.

The next Delta IV Medium is scheduled to launch on July 25, 2019, also from Space Launch Complex 37B.

Video courtesy of SciNews

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Lloyd Campbell’s first interest in space began when he was a very young boy in the 1960s with NASA’s Gemini and Apollo programs. That passion continued in the early 1970s with our continued exploration of our Moon, and was renewed by the Shuttle Program. Having attended the launch of Space Shuttle Discovery on its final two missions, STS-131, and STS-133, he began to do more social networking on space and that developed into writing more in-depth articles. Since then he’s attended the launch of the Mars Science Laboratory Curiosity rover, the agency’s new crew-rated Orion spacecraft on Exploration Flight Test 1, and multiple other uncrewed launches. In addition to writing, Lloyd has also been doing more photography of launches and aviation. He enjoys all aspects of space exploration, both human, and robotic, but his primary passions lie with human exploration and the vehicles, rockets, and other technologies that allow humanity to explore space.

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